In the refining of crude oils the heavy cuts including residue often are subjected to catalytic hydroprocessing to remove such components as sulfur, nitrogen, metals, and Conradson carbon through desulfurization, denitrogenation, demetallization, or asphaltene conversion or any combination thereof. Various types of heterogeneous hydroprocessing catalysts are used to promote these reactions by contacting the catalyst with feedstock under conditions of elevated temperature and pressure and in the presence of hydrogen.
A catalyst that is especially useful in the hydroprocessing of high boiling hydrocarbon feedstocks is disclosed in U.S. Publication 2014/0116924 (Bhan). This catalyst further exhibits the particularly unexpected and unique property of being self-activating in that its activity increases with it use. This catalyst comprises a co-mulled mixture of inorganic oxide powder, molybdenum trioxide powder, and a nickel compound that has been calcined. The calcined co-mulled mixture of the catalyst has specifically defined metal loadings and pore structure.
Another related but different catalyst from the aforementioned is disclosed in U.S. Pat. No. 8,114,806 (Bhan). This catalyst is particularly useful in the processing of disadvantaged crude oils to reduce their viscosity but with minimal amounts of sediment formation and hydrogen consumption to yield a crude oil product having one or more properties enhanced over those of the crude oil that is processed using the catalyst. The catalyst includes one or more metals of the columns 6-10 of the periodic table, such as nickel, molybdenum, cobalt, and tungsten, and it has a specifically defined pore structure. The catalyst is made by co-mulling the metals with a support and the resulting mixture is calcined to give the catalyst.
While the aforementioned catalysts have been shown to have good hydroprocessing activity, there are continuing efforts to find new or improved catalyst compositions having increased catalytic activity or improved stability, or both. Any improvement in catalyst activity can result in lowering of the required reactor temperatures in order to obtain a product of a given nitrogen, sulfur, asphaltene, or metal content from a feedstock that is contaminated with these components. The lower reactor temperatures provide for energy savings and will extend the life of a catalyst. There also are ongoing efforts to find more economical methods of manufacturing the catalyst compositions.
Heavy hydrocarbon feedstocks such as vacuum tower bottoms and resids are typically more difficult to hydrotreat to remove such components as sulfur, nitrogen, metals and carbon than the lighter distillate and naphtha feedstocks. Specially designed catalysts that are different from those used for treating the lighter hydrocarbon feedstocks can be required in order to more economically treat the heavier hydrocarbon feedstocks. So, there is an ongoing need to find new or improve catalyst compositions that have good properties for the hydroprocessing of heavy hydrocarbon feedstocks.
It is, therefore, desirable to provide an improved hydroprocessing catalyst having good catalytic activity and stability and which can be economical to manufacture. One particular desire is to provide a hydroprocessing catalyst that is particularly useful in the hydroprocessing of heavy hydrocarbon feedstocks, and, especially such feedstocks that have exceptionally high sulfur and metals concentrations.
Thus, accordingly, provided is a method of making a self-activating hydroprocessing catalyst having enhanced activity, wherein the method comprises co-mulling an inorganic oxide powder, molybdenum trioxide powder, and a nickel compound to provide a co-mulled mixture; forming the co-mulled mixture into a particle; calcining the particle to provide a calcined particle; and treating the calcined particle with a sulfoxide compound in the presence of molecular hydrogen to provide the self-activating hydroprocessing catalyst.
The self-activating hydroprocessing catalyst of the invention comprises: a calcined particle treated with a sulfoxide compound in the presence of hydrogen, wherein the calcined particle comprises a co-mulled mixture made by co-mulling inorganic oxide powder, molybdenum trioxide powder, and a nickel compound that is formed into a particle of a co-mulled mixture that is thereafter calcined; wherein the calcined particle comprises molybdenum in an amount from 1 to 10 weight percent, nickel in an amount such that the weight ratio of nickel-to-molybdenum is less than 0.4; and wherein the weight percents are for the metal and on the basis of the total weight of the calcined particle.